Many electrical devices have their access control governed by the correct entry of a user name and/or password which are based on a string of symbols, referred to herein as an access entry string. Such devices can include, without limitation, mobile communication devices, computers, including servers hosting websites, such as commercial or government website, or security devices, such as electronic door lock or alarm system. As increasing amount of confidential information because digitized, there is increased risk that hackers can gain access to such information. Unauthorized access can be gained by hacking the user name and/or password, e.g., by guessing, observing or recording the corresponding entry string while it is supplied by an authorized user. For instance, malicious software installed on an electrical device can track and record passwords entries and then an unauthorized user can use the recorded entries to gain access to the electrical device. There is a need to deter such unauthorized access.